This invention relates to data reading device, particularly for optically reading a film information code on the outside surface of a film cartridge.
Proposals have been made for a film cartridge which indicates film data with a pattern formed by the presence and absence of electrically conductive parts. In addition to a conductivity reading, the pattern permits an optical readout on the basis of the differences in reflection factor between a conductive part and a nonconductive part. However, an optical reading film cartridge presents two problems.
The film information pattern is designed to be read by detecting its electrical conductivity. Hence detecting the film data solely in response to reflection factors of the conductive and non-conductive parts tends to result in detection errors because the system cannot discriminate between a cartridge without a data pattern and a cartridge with a data pattern.
A reading error might also be caused by deviation of the distance between the reflecting surface of a cartridge's pattern, and a sensor that detects the reflection factor of the film information code from an apposite range of distance values.
An object of the invention is to improve film data reading devices.
Another object of the invention is to avoid the aforementioned disadvantages.
Yet another object of the invention is to distinguish between cartridges without the film data codes and those carrying film information codes so as to eliminate errors arising from attempts to read cartridges without data codes.
Yet another object of the invention is to eliminate problems arising from inappropriate distances between sensing elements and data codes.